title: Hexabundles: imaging fiber arrays for low-light astronomical applications.
abstract: We demonstrate a novel imaging fiber bundle ("hexabundle") that is suitable for low-light applications in astronomy. The most successful survey instruments at optical-infrared wavelengths use hundreds to thousands of multimode fibers fed to one or more spectrographs. Since most celestial sources are spatially extended on the celestial sphere, a hexabundle provides spectroscopic information at many distinct locations across the source. We discuss two varieties of hexabundles: (i) lightly fused, closely packed, circular cores; (ii) heavily fused non-circular cores with higher fill fractions. In both cases, we find the important result that the cladding can be reduced to ~2 μm over the short fuse length, well below the conventional ~10λ thickness employed more generally, with a consequent gain in fill factor. Over the coming decade, it is to be expected that fiber-based instruments will be upgraded with hexabundles in order to increase the spatial multiplex capability by two or more orders of magnitude.
authors.affiliation: Sydney Institute for Astronomy, School of Physics, University of Sydney, NSW 2006, Australia. jbh@physics.usyd.edu.au
authors.forename: Joss
authors.initials: J
authors.lastname: Bland-Hawthorn
authors.forename: Julia
authors.initials: J
authors.lastname: Bryant
authors.forename: Gordon
authors.initials: G
authors.lastname: Robertson
authors.forename: Peter
authors.initials: P
authors.lastname: Gillingham
authors.forename: John
authors.initials: J
authors.lastname: O'Byrne
authors.forename: Gerald
authors.initials: G
authors.lastname: Cecil
authors.forename: Roger
authors.initials: R
authors.lastname: Haynes
authors.forename: Scott
authors.initials: S
authors.lastname: Croom
authors.forename: Simon
authors.initials: S
authors.lastname: Ellis
authors.forename: Martin
authors.initials: M
authors.lastname: Maack
authors.forename: Peter
authors.initials: P
authors.lastname: Skovgaard
authors.forename: Danny
authors.initials: D
authors.lastname: Noordegraaf
mesh_terms: D001256:Astronomy / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005336:Fiber Optic Technology / Q000295:instrumentation*; D007089:Image Enhancement / Q000295:instrumentation*